and jim axelrod introduces us to math genius john urschel who sure knows how to divide a defensive line. >> i feel like it's what i'm here to do. >> reporter: which one, the football or the math? >> both. capt captioning sponsored by cbs is is the "cbs evening news" this is the "cbs evening news" with scott pelley. >> pelley: good evening, well, the curve was sharp and the train was going way too fast. late today, federal investigators say that the commuter train was bolting down the track at 82 miles an hour as it approaches the 30 miles an hour zone in the bronx, new york, early yesterday. cars from the metro north train flew off the tracks and nearly into the harlem river. four people were killed. some were thrown from the train. 75 others were hurt and 11 of them critically injured. investigators are poring over the data from the trains black boxes to find out why this happened. we have a team of correspondents covering the story starting with jeff pegues at the crash scene. jeff? >> reporter: scott, investigators were able to determine the speed of the train from the black box whic